# STEP to OBJ Converter

> Bring CAD parts into Blender, a renderer or a game engine: STEP to OBJ with every body as its own object and part colors carried over as materials.

Page: https://printpal.io/convert/step-to-obj
Updated: 2026-11-12
Use it: open https://printpal.io/convert/step-to-obj in a browser and drop a file. Free, no account, files are processed locally and never uploaded.

Renderers and game engines want meshes, not B-rep solids. The converter meshes each STEP body with OpenCascade and writes it as a separate object in the OBJ. Colors from AP214 and AP242 files become materials in a .mtl, so you get a .zip with both files.

CAD works in millimetres, so a 120 mm housing becomes 120 OBJ units. Blender reads that as 120 metres; set the import scale to 0.001, or scale the scene. Choose **Y up** in the options if the target app expects it, which is most of them.

## How to convert STEP to OBJ

1. **Drop your STEP files.** Drop .step or .stp files. The STEP reader (about 7 MB) downloads the first time.
2. **Check the preview.** The model appears at the size and orientation it will have. Fix the file units, up axis or size under Size, units and orientation if needed.
3. **Choose OBJ options.** Keep materials on to get a .zip with the .obj, its .mtl and textures. Pick the up axis: Y for Blender and game engines, Z for slicers and CAD.
4. **Convert and download.** One file downloads straight away. A batch gives a download per file and one .zip of all of them.

## What carries over

| | Result |
|---|---|
| Geometry | Exact STEP surfaces are tessellated into triangles with OpenCascade at the quality you pick (Draft, Normal or Fine). |
| Color | Kept: material colors and textures go in a .mtl with PNG textures (you get a .zip); vertex colors are written into the OBJ. |
| Units | OBJ stores no units. The numbers stay in the unit the STEP was read in (millimetres); you can change that in the options. |
| Orientation | Kept the way the STEP had it. Switch to Y up (Blender, game engines) or Z up (slicers, CAD) in the options. |
| Objects | Each part stays a separate object or mesh. |
| Editability | Feature history and exact surfaces are not recoverable from a mesh. Keep the CAD file as your master. |

## STEP at a glance (ISO 10303-21 (Standard for the Exchange of Product model data))

STEP is the ISO standard for exchanging exact CAD geometry. Unlike a mesh it keeps true curves, so a 10 mm hole stays a perfect 10 mm cylinder until something turns it into triangles.

- **Stores:** Exact B-rep solids: planes, cylinders, fillets and splines as math, in assemblies
- **Color:** Per part and per face in AP214 and AP242; none in AP203
- **Units:** Declared in the file, usually millimetres
- **Up axis:** Whatever the CAD used; usually Z
- **Meshing:** Needs tessellation into triangles before printing or rendering
- **Opens in:** SolidWorks, Fusion, Onshape, FreeCAD, Inventor, CATIA, NX; Bambu Studio, OrcaSlicer, PrusaSlicer

## OBJ at a glance (Wavefront OBJ)

OBJ came out of Wavefront Technologies' animation software and became the plain-text lingua franca of 3D. The geometry is in the .obj; colors and texture references live in a companion .mtl file, which is why OBJs so often arrive grey.

- **Stores:** Vertices, faces (triangles, quads, n-gons), UVs and normals as text
- **Color:** Materials and textures in a separate .mtl file; vertex colors as an unofficial extension
- **Units:** None, the numbers are bare
- **Up axis:** Y by convention (Blender, Maya, most 3D apps)
- **File size:** Text: about a binary STL's size for bare geometry, up to twice that with UVs and normals
- **Opens in:** Blender, Maya, 3ds Max, ZBrush, Cinema 4D, game engines, most slicers

## Tips

- **Smooth renders** Use **Fine** quality for close-up renders: curved faces get more, smaller triangles.
- **Parts stay separate** Every body is its own object, so you can hide, move and material each one.
- **No colors in the file?** AP203 STEP has no colors. Assign materials after import.

## FAQ

### Does STEP to OBJ keep colors?

Yes, for STEP files that have them (AP214, AP242). Each color becomes a material in the .mtl.

### Why is my OBJ huge in Blender?

CAD is in millimetres and OBJ has no units, so Blender reads millimetres as metres. Import with a scale of 0.001.

### Can I edit the CAD features afterwards?

No. The OBJ is a mesh; keep the STEP for CAD edits.

### Is the converter free? Are there limits?

Free, with no sign-up, watermark or file count limit. Batches and files of a few hundred MB work on most laptops; the only limit is your device's memory.

### Are my files uploaded?

No. Files are read and written by JavaScript and WebAssembly in your browser and never sent to PrintPal. The STEP and IGES reader is the only extra download, once, from a public CDN.

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